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How coconut husks can cut farm costs and rebuild soil

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Dr. Teodoro Mendoza PhD

Agroecology operationalizes the circular economy at the field level through recycling, efficiency, diversity, synergy and soil regeneration.

In coconut farms in Makilala, Cotabato; Magsaysay, Davao del Sur; and Davao Occidental, the linear economy remains dominant: Farmers sell husks to coir buyers for P0.25 apiece, treating the proceeds as income even as nutrients and other farm resources leave with the husks.

A hectare producing 8,000 nuts yields about 3.2 tons of husks a year. The husks contain nitrogen, phosphorus, potassium and carbon that would otherwise remain on the farm. The manuscript estimates the nutrient value removed at P8,100 a hectare a year, including P5,376 for potassium.

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Husks used as mulch can also increase soil moisture during dry months, reduce weeds and serve as growing media for vegetables such as lubi-lubi, gabi and kangkong.

Why circularity matters

The Ellen MacArthur Foundation describes the circular economy as a system in which waste is designed out, materials are kept in use and natural systems are regenerated.

At the field level, agroecology applies these principles through recycling, efficiency, diversity, synergy and regeneration. The Food and Agriculture Organization identifies similar principles in its framework on the elements of agroecology, while agroecology scholars Miguel Altieri and Peter Rosset have written about its role in building more sustainable agricultural systems.

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Coconut farming can provide a model of circularity when the whole nut — husk, shell, meat and water — is used within the farm. Yet farms visited in Makilala, Cotabato; Magsaysay, Davao del Sur; and Davao Occidental showed the opposite practice.

Farmer A operates 1.5 hectares with 214 coconut trees producing about 80 nuts per tree per year, or about 17,142 nuts. He sells husks to a trader for P0.25 apiece and buys six bags of 14-14-14 fertilizer for coconut and banana.

His soil test showed 1.9% organic matter and potassium deficiency.

Farmer B, with a farm of the same size, keeps the husks, chops them and uses them as mulch between rows. He makes biochar from coconut shells in a simple drum kiln and composts husks with manure.

He uses neither herbicide nor chemical fertilizer, relying instead on labor for mulching. His soil organic matter was measured at 4.1%, with coconut yield at 90 nuts per tree, alongside 400 intercropped banana hills.

This report examines why selling coconut husks while buying chemical inputs creates agronomic and economic leakage.

Linear vs. circular

The linear model follows a take-make-dispose pattern.

Nutrients are taken from the soil through coconut production. The nuts are processed, the husks are sold, and money from the sale is used to buy chemical inputs. Nutrients leave the farm, money is spent on external inputs and soil quality declines.

The circular model follows a take-make-return-regenerate pattern.

The coconut is harvested, but the husk is returned to the field as mulch. Shells are converted into biochar. Cocopeat becomes growing media for vegetables such as lubi-lubi, gabi, sitao and eggplant. Coconut water can be used as foliar feed, while fronds can serve as mulch.

In this model, nutrients remain on the farm, external spending is reduced and the soil is regenerated.

The approach is consistent with circular-economy principles described by the Ellen MacArthur Foundation and with recycling and resource-efficiency concepts identified by the FAO in its agroecology framework.

The difference between the two systems can be measured through nutrient retention, including nitrogen, phosphorus and potassium, as well as changes in soil organic matter.

Nutrient losses

On a dry basis, mature coconut husk contains about 0.8% nitrogen, 0.1% phosphorus, 1.8% potassium oxide, or K2O, and 40% carbon, with a carbon-to-nitrogen ratio of 45:1.

The Philippine Coconut Authority has documented coconut nutrient composition and husk utilization, while research cited in the manuscript by S. Patil and co-authors examined coconut husk as a source of potassium.

Using the van Bemmelen factor of 1.724, 40% carbon is equivalent to about 69% organic matter.

For a typical smallholder yield of 8,000 nuts a hectare a year, the husks account for about 3,200 kilograms of dry matter, or about 0.4 kg per husk.

If those husks are removed, the farm exports an estimated 25.6 kg of nitrogen, 3.2 kg of phosphorus, 57.6 kg of K2O and 1,280 kg of carbon.

The 57.6 kg of K2O is equivalent to 96 kg of muriate of potash, or 0-0-60 fertilizer, because muriate of potash contains 60% K2O.

If 8,000 husks are sold at P0.25 apiece, the farmer receives P2,000.

Using 2026 fertilizer prices in Mindanao cited from the Department of Agriculture’s fertilizer price monitoring, the estimated nutrient value removed from the farm is about P8,100 a hectare a year. This includes P2,276 for nitrogen, P448 for phosphorus and P5,376 for potassium.

Even if only 80% of the husks are collected and sold because of field losses, the nutrient loss remains substantial.

Replacing potassium alone would require about two bags of muriate of potash at P2,800 each, or P5,600. That already exceeds the P2,000 received from selling 8,000 husks, even before the value of nitrogen, phosphorus, organic matter and water retention is included.

Coconut husk also has substantial water-holding capacity. One kilogram of husk can retain about 8 liters of water as cocopeat. Used as mulch, the manuscript estimates that it can increase soil moisture by 38% during dry months, equivalent to about P6,000 in irrigation savings based on 30 days of pumping at P200 a day.

Research on mulching and conservation agriculture cited in the manuscript, including work by Christian Thierfelder and co-authors, examined the effects of mulch on soil conditions.

Herbicide use compounds the leakage.

The manuscript states that glyphosate application reduces populations of earthworms and lignin-decomposing fungi needed to break down coconut husk. Coconut husk has lignin content of about 30%.

Under the conditions cited, decomposition of husk mulch takes about six months in biologically active soil with 3% organic matter, compared with about 14 months in soil where biological activity has been suppressed.

The result is a double loss: The farmer removes the nutrient source by selling the husk while also reducing the organisms needed to recycle organic material in the soil.

The manuscript also estimates that 14-14-14 fertilizer applied to coconut has a use efficiency of only 30% to 35% in soil with organic matter of about 1.9%. In soil with about 3% organic matter, efficiency is estimated at 55% to 60% because organic matter improves cation exchange capacity and helps buffer soil pH.

Under this model, a farmer retaining husks would need only three bags of fertilizer instead of six to achieve the same yield, producing an estimated savings of P5,400.

Returning 3,200 kg of husks to the field also returns about 2,208 kg of organic matter a hectare a year.

Economic losses

At a uniform coconut price of P10 per nut, a linear farm producing 7,000 nuts generates P70,000 from coconut sales plus P1,750 from the sale of husks at P0.25 apiece, for gross income of P71,750.

Its annual costs are estimated at P52,100: P4,800 for herbicide, P1,500 for spraying labor, P10,800 for six bags of fertilizer, P21,000 for harvesting and P14,000 for dehusking.

Net income is therefore P19,650 a hectare a year, or about P54 a day.

Under the circular model, the farm keeps its husks and receives no income from husk sales.

Gross income consists of P70,000 from 7,000 coconuts at P10 each, P120,000 from 400 banana hills at a net P300 per hill and P60,000 from vegetables such as lubi-lubi, gabi and kangkong grown using husk peat media. Total gross income is P250,000.

Costs are estimated at P49,000: P12,000 for mulching labor, P2,000 for biochar kiln labor, P21,000 for harvesting and P14,000 for dehusking.

The model assumes no spending on herbicide or chemical fertilizer because compost, mulch and biochar derived from husks and shells replace them.

Net income is therefore P201,000 a hectare a year, or about P550 a day.

The difference between the two systems is P181,350 a hectare a year in favor of the circular model.

The manuscript attributes that difference to additional income from banana and vegetable production, savings on herbicide and fertilizer, additional labor costs for mulching and biochar production, and foregone income from husk sales.

The circular farm also builds a soil asset by returning carbon to the field as mulch and biochar rather than exporting it.

Ecological costs

Selling coconut husks removes potassium, an important nutrient for coconut production.

In the monitored farms cited in the manuscript, soil potassium declined from 120 parts per million to 65 ppm over five years, contributing to button shedding and low nut set.

Herbicide use also removes understory plants that can serve as food and additional sources of income, including lubi-lubi fern, gabi and upland kangkong.

The manuscript states that chemical fertilizer use can contribute to soil acidification, with soil pH declining from 5.8 to 4.9 over three years under the conditions observed. Lower pH can reduce potassium and phosphorus availability while increasing aluminum toxicity, affecting cacao and banana intercrops.

Removing 1,280 kg of carbon in husks from a hectare each year also means losing material that could otherwise contribute to soil organic matter or be converted into biochar.

The International Biochar Initiative, cited in the manuscript for information on biochar made from coconut shell and carbon sequestration, has documented the use of biochar as a stable form of carbon.

If the husks are burned inefficiently as fuel, the manuscript estimates emissions equivalent to 4.7 tons of carbon dioxide. If converted into biochar, a portion of the carbon can remain stable in the soil for an extended period.

Circular farm practices

Farms practicing circularity used several approaches.

Husks as mulch. Chopped husks are applied about 5 centimeters thick between rows. The practice increases moisture retention, reduces weeding and gradually releases potassium as the material decomposes.

The use of mulch to improve soil conditions is also reflected in the conservation-agriculture research by Thierfelder and co-authors cited in the manuscript.

Husks as cocopeat. Processed husks provide growing media for vegetable nurseries. One kilogram of cocopeat can hold about 8 liters of water and can be used for crops such as lubi-lubi and gabi.

Shells as biochar. A simple 200-liter drum kiln can convert coconut shells into biochar. The manuscript estimates a yield of about 30 kg of biochar for every 100 kg of shells.

The International Biochar Initiative is among the sources cited in the manuscript on the conversion of coconut shell into biochar and its carbon-sequestration potential.

Applied at about 2 kg per tree a year, biochar is described as improving water-holding capacity and cation exchange capacity.

Husks and fronds as vermicompost. Chopped husks and manure can be fed to African night crawlers to produce vermicompost. The system described in the manuscript produces about 5 tons of vermicompost a hectare a year, estimated to be equivalent to four bags of fertilizer.

Cover crops instead of herbicide. Camote and kangkong are used as living mulch to suppress weeds, provide food and protect the soil.

These practices reflect the circular-economy principle of keeping biological materials in productive use and the recycling principles identified by the FAO in its agroecology framework.

Selling coconut husks while buying herbicides and chemical fertilizers, by contrast, exports nutrients and carbon from the farm while creating demand for purchased inputs.

The manuscript estimates that a farmer selling 3,200 kg of husks a hectare a year from 8,000 nuts receives about P1,750 to P2,000, while exporting nutrients worth about P8,100.

The farmer may then spend P5,600 on two bags of muriate of potash, P10,800 on six bags of 14-14-14 fertilizer and P6,300 on herbicide and spraying labor.

Under this model, income from husk sales is outweighed by the cost of replacing nutrients and managing weeds after biomass has been removed.

The manuscript describes this as linear-economy leakage: Money leaves the farm for external inputs while the soil loses nutrients and organic material.

It also cites trader debt averaging P22,400 at 5% monthly interest among agrarian reform beneficiaries in Davao, with standing coconut crops used as collateral.

Keeping biomass on the farm is presented as a way to reduce dependence on such external inputs and credit.

A 5-cm layer of chopped husk mulch can suppress weeds, improve soil moisture during dry periods and gradually release potassium.

Coconut shells can be converted into biochar using a 200-liter drum kiln fabricated from scrap materials. The manuscript estimates that 100 kg of shells produces about 30 kg of biochar.

Cocopeat can be used to grow lubi-lubi, gabi, kangkong, camote and other vegetables, providing an additional income stream.

Husks and fronds can also be vermicomposted with manure to produce organic fertilizer using family labor.

Together, these practices form the circular model described in the manuscript, generating an estimated net income of P201,000 a hectare a year at P10 per nut, compared with P19,650 under the linear model.

Policy recommendations

Recommendations for implementing circularity should address policy, incentives, capacity and demonstration.

First, local governments in the Davao region should consider ordinances discouraging bulk husk sales unless an equivalent amount of processed organic material is returned to farms.

The proposed ordinance would require traders buying more than 500 husks in a transaction to return 30% by weight as biochar or compost or pay a P2-per-husk environmental fee to a barangay composting facility.

The proposal is intended to account for nutrient value that is otherwise removed from farms and could be monitored by barangay agricultural extension workers using weighing scales.

Second, the Philippine Coconut Authority should consider paying farmers P2 for every husk returned to the farm as mulch as an ecosystem service incentive.

The PCA is also among the sources cited in the manuscript on coconut nutrient composition and husk utilization.

For a farmer mulching 8,000 husks, the payment would amount to P16,000 a hectare a year. Compliance could be documented through geotagged photographs of mulched rows submitted through the PCA mobile application.

The recommendation is intended to shift support from purchased chemical inputs toward soil regeneration.

Third, herbicide spraying should be prohibited on coconut intercrop farms receiving Department of Agriculture support under programs including Gulayan sa Paaralan, the Coconut Farmers and Industry Development Plan and Kadiwa.

Under the proposal, zero herbicide use would be a condition for receiving cacao seedlings, grafted durian planting materials and vegetable seeds because spray drift can damage intercrops.

Compliance could be verified through barangay certification and the presence of living ground cover and intercrops.

Fourth, training in biochar kiln fabrication using scrap drums should be expanded through the Technical Education and Skills Development Authority and Agricultural Training Institute.

The design described in the manuscript uses a 200-liter oil drum with eight holes at the bottom and a chimney made from galvanized iron pipe. It takes about four hours to produce biochar at an estimated 30% yield.

The estimated fabrication cost is P1,200 — P800 for a scrap drum and P400 for welding labor.

A proposed two-day training module would cover safety, feedstock preparation, an application rate of 2 kg per tree and cocopeat production.

Fifth, school gardens should demonstrate the circular model by using coconut husk peat to grow lubi-lubi and other indigenous vegetables.

Under the proposal, schools would collect about 200 husks from nearby farms, produce cocopeat and grow crops including lubi-lubi fern, gabi, malunggay and upland kangkong in plots measuring 1 meter by 10 meters.

Students could measure plant growth, water retention and income from produce while learning how agricultural residues can be reused within a farm system.

Conclusion

Agroecology applies circular-economy principles at the field level by recycling biomass, closing nutrient loops, diversifying production and reducing dependence on external inputs.

The framework draws on circular-economy concepts identified by the Ellen MacArthur Foundation and agroecological principles described by the FAO and scholars including Altieri and Rosset.

In coconut farms visited in Makilala, Cotabato; Magsaysay, Davao del Sur; and Davao Occidental, selling coconut husks to coir buyers for P0.25 apiece represents the linear model examined in this report.

For a hectare producing 8,000 nuts, about 3.2 tons of husks are removed each year. The manuscript estimates that those husks contain 25.6 kg of nitrogen, 3.2 kg of phosphorus, 57.6 kg of K2O and 1,280 kg of carbon.

Information cited from the Philippine Coconut Authority and the study by Patil and co-authors supports the manuscript’s treatment of coconut husk as a source of nutrients, particularly potassium.

Using Department of Agriculture fertilizer prices cited in the manuscript, the estimated nutrient-replacement value is P8,100 a hectare a year, including P5,376 for potassium.

Used as mulch, the same biomass can improve soil moisture during dry periods, suppress weeds and reduce the need for herbicide. Processed into cocopeat, it can provide growing media for vegetables. Coconut shells can be converted into biochar, while husks and fronds can be composted.

Under the economic comparison presented here, the linear farm generates P19,650 in annual net income at a coconut price of P10 per nut. The circular farm generates P201,000, including income from banana and vegetable intercrops, for a difference of P181,350 a hectare a year.

The circular model also retains carbon and nutrients that would otherwise leave the farm.

The manuscript argues that the price paid for coconut husks should reflect the nutrient and ecological value removed from the farm. It proposes a minimum price of P2.50 per husk or the return of an equivalent amount of biochar when husks are purchased by traders.

Its central principle is that retaining coconut biomass allows farmers to keep nutrients, water-holding capacity, food production and income within the farm.

Agroecology, in this framework, turns the circular economy into field-level practice through recycling, efficiency, diversity, synergy and soil regeneration. /dm

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(Teodoro C. Mendoza is a retired professor and scientist of the Institute of Crop Science, College of Agriculture and Food Sciences, UP Los Baños, Laguna)

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